my property appreciation varies from a low of $2700/month to over $10k/month.   

Depends on carrier.

You should have a good idea of every expense you have in your primary home, then add the STR specific:  (These are rough estimate numbers, depending on various factors)STR insurance - a special insurance that covers both the property and your liability, could be $2~4k in areas without natural disasters, could be more than $10k in some other areas.cleaning fee - approx. $50 per bedroom, so a 4-bedroom house will cost you about $150~200consumables - bathroom supplies, kitchen supplies, beverage supplies: $20~30 per week, depending on how much you providewear and tear - towels, linen, kitchen utensils, some furniture: $1000~2000 per yearRepairs/replacement for things that guests break or steal:  $1000~2000 per yearAlso, if your personal use is less than 14 days a year, the entire property's expense is deductible against STR income, but if you use more than 14 days, then you will have to calculate the proportion of how many days it's rented out vs how many days you or your family uses. 

Sometimes it's device dependent (either browser or phone problems).

Refi after construction.These numbers consider only the portion of costs of the HEL attributable to the land purchase, not the payoff of the HELOC (which we took out to buy the Seaside condo).Cash In:                     $66,166 (Cash, 1 year of debt service of HEL, debt service of const. loan, furnishing)Amount Financed:      $548,000 (home equity loan + construction loan + closing costs)Total Cost of build:     $614,166ARV:                               $850,000 (or rather "after construction value")Refi                                $637,500 (75% of value + closing costs)                                        Cash Out                       $89,500New payment             $4500/month (54,000/year)Estimated Cash Flow (pre-tax numbers, so actual mileage may vary)airBNB year 1:            $70,000     (net income $16,000)airBNB year 2:            $100,000   (net income $46,000)airBNB year3+:           $120,000   (net income $66,000)ROI (construction year):    0ROI Year 1 of STR:              24.2% ROI Year 2 of STR:              69.5% ROI Year 3+ of STR:            99.7% Did I calculate these ROI numbers right? 

@Chris Kay it depends what level of renovation you are doing!

Selling for $380k means an $80k taxable gain at long-term capital gains rates (0%, 15%, or 20%, depending on income).The $80k HELOC used for personal debts doesn’t affect your taxes.A 1031 exchange could defer taxes, but you’d need to reinvest in another investment property, not a home for your mom.

I think it really depends the style and setup.

All of this really depends on your goals and timeline though too.

It looks like Kevin's and my markets vary.